A road traffic requirement in several European countries is the carrying by motor vehicles of a warning triangle and its deployment, e.g. at 50-100 m, behind a broken-down or otherwise stationery vehicle. Such warning triangles carry reflective material and rely for their warning effect on illumination by the headlights of an on-coming vehicle, and hence constitutes in effect little more than a deployable reflective road stud using old technology.
In addition, it is also known to equip emergency motor vehicles with battery powered lighting units for deployment, e.g. at a road accident. However, such units are relatively bulky and consume valuable storage space of emergency vehicles. Also, the existing systems normally require the batteries to be replaced at regular intervals. Unfortunately, in practice, the life left in the batteries is only normally checked when the unit is about to be used, and vital minutes are lost replacing the batteries at what is usually the most dangerous period of the emergency.
Furthermore, when transporting known battery units from the emergency vehicle to the intended deployment location, due to their bulk and weight only two units can be normally carried by one person at any one time, usually resulting in the need to make repeated journeys, and frequently, emergency vehicles cannot be located in close proximity to the required deployment location.